1. Field of the Invention
The present invention relates to a two-parallel-channel reflector (TPCR) with focal length and disparity control, and in particular, to a TPCR with focal length and disparity control, having two parallel channels that allow an imaging device to capture a left side view image and a right side view image of a shot scene synchronously and capable of adjusting a position and an angle of an outward reflecting unit according to imaging requirements during imaging to control the disparity and the focal length.
2. Related Art
Conventional computer stereo vision uses two or more imaging devices such as two or more cameras to shoot images of the same scene from different view angles. The imaging devices are separated by a suitable distance, like human eyes. When a person views an object, a disparity effect is generated because of a distance between the eyes, thus the image has a stereoscopic impression. Accordingly, after each imaging device respectively performs imaging through analysis and calculation of computer software, the depth of the scene in the picture may be calculated with the principle similar to the human eye disparity, so as to generate images-plus-depth information. Therefore, with the image obtained by each imaging device and the calculated images-plus-depth information, a digital stereo image may be generated. Currently, the relevant conventional technologies include:
(1) a two-channel multi-view imaging system patented by Andre Redert and Emile Hendriks in 2003, where reference may be made to U.S. Pat. No. 6,643,396 “Acquisition of 3-D Scenes with a Single Hand Held Camera”; and
(2) a single hand held camera installed on a reflector patented by Pieter O. Zanen, where reference may be made to U.S. Pat. No. 5,532,777 “Single lens apparatus for three-dimensional imaging having focus-related convergence compensation”.
Referring to FIG. 1, in a two-channel multi-view imaging system 1, a hand held camera 11 is installed on a reflector 12 patented by Pieter O. Zanen. The reflector 12 has two imaging channels (a left imaging channel 121 and a right imaging channel 122), and each channel is bounded by two flat reflecting mirrors. As shown in FIG. 1, the left imaging channel 121 is bounded by a first center mirror 1211 and a left mirror 1212, and the right imaging channel 122 is bounded by a second center mirror 1221 and a right mirror 1222. Light rays L1 (or captured images) entering the left imaging channel 121 arrive at the left mirror 1212, are reflected to the first center mirror 1211, and are then reflected to the camera 11. Light rays L2 entering the right imaging channel 122 arrive at the right mirror 1222, are reflected to the second center mirror 1221, and are then reflected to the camera 11. Hence, an image generated by Redert/Hendricks' imaging system 1 at least contains two views of the scene, that is, a left view and a right view. That is, the imaging system 1 can obtain images of different view angles synchronously by using only one camera. However, the two imaging channels of the imaging system 1 are constructed by flat reflecting mirrors, in which the problem that miniaturization cannot be achieved exists. FIG. 2 is a schematic diagram of optical paths of the conventional imaging system. Referring to FIG. 2, the center mirrors (1211, 1221) and the side mirrors (1212, 1222) are all flat, so that, for the purpose of obtaining complete imaging and satisfying a large focal length range during imaging, the sizes of the center mirrors (1211, 1221) and the side mirrors (1212, 1222) should be as large as possible to adapt to the angles of incidence and reflection of the light rays and the images. As a result, the entire dimension of the finished product, for example, the thickness d1, is quite large, which not only occupies a large space, but also causes inconveniences in use. On the contrary, if the sizes of the center mirrors (1211, 1221) and the side mirrors (1212, 1222) are reduced, the focal length during imaging is limited.
An improvement of Redert and Hendriks' approach was patented by Shuzo Seo in 2005, where reference may be made to U.S. Pat. No. 6,915,073 “Stereo Camera and Automatic Convergence Adjusting Device”. In the technology disclosed in this patent, a pivot mechanism is added to the two-channel reflector so that outward mirrors can be rotated about the pivot mechanism. This rotation process is automatically performed when lens of the camera are zoomed. As a result, the focal length of the two-channel reflector can be automatically adjusted. This is an important invention on single-lens, multi-view imaging process. However, unfortunately, due to the fact that flat mirrors are used for both outward reflecting and inward reflecting, this technology cannot adjust the disparity of the reflector either.